Part of this is due to the fact that there isn't (and probably shouldn't be) a singular national system for education. Another part is the fact that quality education is insanely high-priced because a parent has to pay for the public and the private system concurrently. This pressure pushes private tuitions upward and makes the private schools more exclusive because they can't take on kids below certain income thresholds at all.
This is one case where I believe regulation has actually hurt the US citizens a lot. No child left behind was a staggering failure, and most people would be better off making their educational choices for their children based on what makes the most sense for them, not based on a legislated prescription of certain topics (or the intentional avoidance of others, namely human health and biology...)